1. Field of the Invention
The present disclosure relates to a load compensating device in railway vehicles.
2. Description of Related Art
This section provides background information related to the present disclosure, which is not necessarily prior art.
Weights of each individual railway vehicle change in response to loading or unloading of passengers in railway vehicles transporting passengers, and weights of each individual railway vehicle change in response to quantity of loads in cargo railway vehicles transporting cargos. Generally, railway vehicles are equipped with a loading compensating device detecting a weight of an individual railway vehicle in response to changes in loads.
The load compensating device is equipped with an air spring and a pressure sensor measuring a pressure of the air spring, where the load compensating device detects changes in loads by detecting a pressure of the air spring changing in response to the changes in loads. The load compensating device is connected to a brake system to act as one of elements in performing a service brake and an emergency brake. That is, the air spring of the load compensating device detects pressures in response to changes in weights of passengers, and is used in calculating a consumed braking force of a service brake device to allow the railway vehicles to have a predetermined deceleration regardless of loads or weights of the passengers, or operates a load valve by being connected to an emergency brake device.
FIG. 1 is a block diagram illustrating a load compensating device according to prior art. Referring to FIG. 1, a pressure sensor 110 measures a pressure of an air spring and measures the changing loads of railway vehicles, in a case the loads of railway vehicles change in response to loading and unloading of passengers. In a case the pressure based on the changing loads of railway vehicle is received through the pressure sensor 110, a load converter 120 compares the pressure with an empty load limit and a full load limit.
In a case the pressure of the air spring is in between the empty load limit and the full load limit, the pressure is provided to a braking system for use in calculating consumed braking force of service braking device, or in realizing an emergency braking force of an emergency braking device.
The load compensating device thus explained according to prior art 100 performs an empty load warrantee and a full load warrantee in preparation for any fault in the pressure sensor 110. By way of non-limiting example, in a case the detected pressure of air spring is less than 90% of pressure of air spring during empty load, the load compensating device outputs a pressure at a rate of 90% pressure of empty load, and in a case the detected pressure of air spring is more than 120% of pressure of air spring during full load, the load compensating device outputs a pressure at a rate of 120% pressure of full load. As noted above, the load compensating device according to prior art 100 warrantees a limit value such as the empty load limit or the full load limit during fault of the pressure sensor 110.
However, the abovementioned method suffers from disadvantages in that an actual weight of railway vehicle cannot be reflected during calculation of consumed braking force in the braking device, in a case a bias error is present during occurrence of fault in the load compensating device or during measurement of a value of pressure sensor, such that same deceleration cannot be reflected on each railway vehicle to disable reflection of appropriate consumed braking force. As a result, it is difficult to perform a smooth braking operation, or a braking distance is lengthened due to failure in obtaining a necessary braking force.